abstract
White light-emitting diodes (WLEDs) are candidates to revolutionize the lighting industry towards energy efficient and environmental friendly lighting and displays. The current challenges in WLEDs encompass high luminous efficiency, chromatic stability, high colour-rending index and price competitiveness. Recently, the development of efficient and low-cost downconverting photoluminescent phosphors for ultraviolet/blue to white light conversion was highly investigated. Here we report a simple route to design high-efficient WLEDs by combining a commercial ultraviolet LED chip (InGaAsN, 390 nm) and boehmite (gamma-AlOOH) hybrid nanoplates. Unusually high quantum yields (eta(yield) = 38-58%) result from a synergic energy transfer between the boehmite-related states and the triplet states of the benzoate ligands bound to the surface of the nanoplates. The nanoplates with eta(yield) = 38% are able to emit white light with Commission International de l'Eclairage coordinates, colour-rendering index and correlated colour temperature values of (0.32, 0.33), 85.5 and 6,111 K, respectively; overwhelming state-of-the-art single-phase ultraviolet-pumped WLEDs phosphors.
keywords
LIGHT-EMITTING-DIODES; INTRAMOLECULAR ENERGY-TRANSFER; CHARGE-TRANSFER STATE; ONE-STEP SYNTHESIS; OPTICAL-PROPERTIES; BLUE PHOTOLUMINESCENCE; MN2+ PHOSPHORS; QUANTUM DOTS; F-CENTER; LUMINESCENCE
subject category
Science & Technology - Other Topics
authors
Bai, X; Caputo, G; Hao, ZD; Freitas, VT; Zhang, JH; Longo, RL; Malta, OL; Ferreira, RAS; Pinna, N
our authors
Maria Rute de Amorim e Sá Ferreira André
Full professor
Vânia Patrícia Castro Teixeira Freitas
Research Fellowship
Xue Bai
Post-doc Fellowshipacknowledgements
This work was partially supported by the National Science Foundation of China (Grant Nos. 11174111 and 11274007), FEDER, COMPETE, FCT (SFRH/BPD/71671/2010, SFRH/BD/87403/2012, PEst-C/CTM/LA0011/2013) and PRONEX/FACEPE-CNPq APQ-0859-1.06/08 and INCT-INAMI/MCTI. Professor Dr Nikolaus Ernsting, PD. Dr Gudrun Scholz, Felix Klein and Dr Donato E. Conte from the Humboldt-Universitat zu Berlin are acknowledged for critical reading of the manuscript and fruitful discussions, solid-state NMR and fruitful discussions, support with synthesis, and Rietveld refinements, respectively. Professor Dr Luis D. Carlos from the University of Aveiro is acknowledged for fruitful discussions concerning photoluminescence data.